I have worked at Mesa for nearly 4 years. All I can say is: Stay away. Stay very far away. After jobs with a few large corporations and one 135 Fr8 op all I can say is that in my humble opinion, Mesa defines the lower limit on the bell curve of bad companies.
Mesa will ruin your life and by the end of your first year will pray every day that you can find some other airline to work for....
Its like that scene in Stripes, Bill Murray is trying to rally the troops and he says something like: "We're not Watusi, but we have one thing in common, we were all stupid enough to join the army..." Just sub Mesa with Army and you'll see what I mean,
You will like nearly everyone you fly with, but you will absolutely hate working for Mesa.
Good luck, you'll need it.